114 Sef/regation of Fecundity Factors in Drosophila 



showed that tlieir completeness depended on hick and not on any 

 knowledge possessed by the writer. 



Table I presents the data fioni Line I, the strain lacking in vigor. 

 Four pairs were mated, they being respectively designated as A, B, 



G and D. The table shows the low state of their fecundity and also 

 the degree to which they bred true. Placed on the basis of the 

 means, for comparative purposes, the last eight generations rank as 

 follows : 



The mean of the entire line, nine generations, is 29-5 and the 

 standard deviation is 7-31, giving as coefficient of variability 28-17. 

 The coefficient of variability is of little value as a means of comparing 

 the different lines owing to the fact that the units of variation are the 

 same and the means so widely separated. Thei-efore it would seem 



